Radiator rod assembly



June 5 1934. R. T. HUMMEL RADIATOR ROD ASSEMBLY Filed May 13 1932 INVENTOR FdiE/W" Z' lV/VEL W 9 J6 lil ATTO@ temperature.

Patented June 5, 1934 UNITE STATES OFFICE Westinghouse Lamp of Pennsylvania 7 Company, a corporation Application May 13, 1932, Serial No. 611,124

2 Claims.

This invention relates to electrical discharge devices and is especially directed to devices of this character where it is important to maintain an element thereof below a predetermined In its more specific aspect, the invention is directed to an X-ray tube and especially the radiator associated therewith.

One type of X-ray tube generally employed in the radiographic field comprises an elongated envelope having a re-entrant tube at its lower end. A relatively thin tubular metallic supporting member with a nipple has its lower edge sealed to the upper edge of the re-entrant tube in the form of a gas-tight metallic, copper, glass bead. Threadedly secured to the outer portion of the nipple of the tubular support is an anode of substantial mass having a target embedded in the free end thereof. Within the envelope and located above the free or target end of the anode, is a filamentary cathode adapted to become incandesced. By means of a suitable potential, as for example 40,900 volts or more, being applied between the anode and the cathode, the electrons emanating at the incandescent cathode are driven towards the \anode and there strike the target to produce X-ray emissions therefrom. During the period the electrons strike this target, it is found that the temperature of the target rises. In order that this target may not attain such a temperature as to cause a fusion or material erosion thereof, the mass of the anode proper is of relatively large proportions as compared to the mass of the target per se so that the heat capacity of the anode proper is relatively high as compared to that of the target.

In practice it has been found that there are practical limitations as to the length of the anode, which therefore necessitated the employment of means for dissipating some of the heat energy evolved at the target and conducted throughout the anode body. For this purpose it has heretofore been customary to provide a solid copper radiator rod having a threaded projection at its upper end and having a fin radiator secured to its lower end.

When X-ray tubes embodying a cathode and an anode suitably supported within an envelope, are in the process of manufacture, the radiator rod together with the fin radiator is secured to the tubular supporting member by screwing the small projection of the radiator rod into the hollow projection portion or nipple of the tubular anode supporting member. The upper end of the radiator rod at the lower portion of the threaded projection is in the form of. a shoulder which contacts the under face of the tubular member when the radiator rod is secured thereto.

In order that the radiator rod may effectively serve its purpose, it is essential that it be in firm contact with the tubular supporting member. Thus, it is necessary that the radiator rod be screwed tightly thereto. In the commercial production of devices of this character, and especially during the assembly of the radiator rod with the tube proper, it has been found that in the attempt to get a firm contact by screwing the radiator rod into the nipple of the tubular member that the copper-glass seal and/or the tubular member is sometimes impaired. This, I believe, is due to the fact that the shoulder of the radiator rod is in contact with the lower portion of the tubular member in the course of rotation of said radiator rod during the screwing operation so as to cause a distortion of said tubular member and/or seal impairment which is sometimes evidenced as seal fracture.

My invention is directed to the provision of a novel simple assembly which may be carried out without these dangers of seal fracture.

Briefly stated, my invention is directed to an electrical discharge device having a radiator rod assembled therewith which assembly may be produced without the danger of distorting the tubular anode supporting member or of seal impairment. These results I obtain by employing a novel means which, upon assembly with the discharge device per se, applies a force in the direction of the longitudinal axis of the tubular member so as to eliminate substantially all tendencies to subject said tubular member to torsional forces.

An object of my invention is to provide an electrical discharge device having a radiator rod secured thereto which may be assembledtherewith without causing excessive torsional strains in a supporting member.

Another object of my invention is to provide an electrical discharge device having a radiator rod associated therewith which assembly may be expeditiously carried out to ensure a good heat conducting path between the radiator rod and the anode without causing the anode supporting member from being subjected to excessive torsional strains.

Another object of my invention is to provide an X-ray tube having a relatively thin tubular member, supporting an anode and a radiator,

' and shock-absorbing plates (not shown).

rod, which assembly may be readily carried out without subjecting the support member to excessive torsional strains and at the same time provide a good thermal path between the radiator rod and the anode.

Other objects and advantages of my invention will become apparent from the following description and appended drawing wherein:

Fig. 1 represents a fragmentary longitudinal cross-sectional view with some of the parts in elevation of an X-ray tube embodying my invention;

Fig. 2 represents a cross-sectional view along the line 2-2 taken on Fig. 1 in the direction of the arrows.

As shown in Fig. 1, the X-ray tube may comprise a glass envelope 10 having a body portion of generally cylindrical form with a hemispherical portion at one end and a re-entrant tube 11 at its other end. To this re-entrant tube is hermetically sealed a tubular metallic and preferably copper, sleeve or support cup 12. This sleeve or support cup 12 has a thin annular portion to which the upper end of the re-entrant tube 11 is hermetically sealed by following the common process generally employed for this purpose. This sleeve or support coupling 12 has a nipple or hollow projection 13 whose outer surface as well as its recessed portion is threaded.

A copper shielding means 14 having an opening therein of a diameter slightly greater than the corresponding external dimension of the hollow projection or nipple 13 rests on and is supported by the shoulder or" the tubular sleeve or support member 12 with the hollow projection or nipple 13 extending through this opening. Mounted on said sleeve or support member 12 is an anode 15 which is threadedly secured to the hollow projection or nipple 13 by virtue of a threaded engagement between the threads on a longitudinal recess in the anode and the threads on the outer portion of the nipple. This anode may be of any suitable metallic material and preferably of copper and extends upwardly Within the envelope and along the longitudinal axis thereof.

The upper free end of the anode 15 has a target 16 of suitable material, as for example, tungsten or the like embedded therein and serves as an X-ray emitting material upon bombardment thereof by the electrons from a suitable filamentary cathode 1'7. Disposed around and having its interior wall spaced from the free end of the anode 15, is an X-ray screen 18 consisting of chrome iron. This X-ray screen houses the cathode 17 and a focusing cup 19. The cathode 17 is electrically secured to contact caps 20 and 21 respectively. Surrounding this metallic screen and functioning to provide a screen supporting and shock absorbing means are a plurality of resilient plates 22 which bear against the outer surface of said screen and the interior of the envelope.

Located within the envelope and extending upwardly therewithin, is a second re-entrant tube 23 surrounding and spaced from the tubular sleeve 12 and the anode 15. This re-entrant tube is of material length and has its lower edge fusedly united with the envelope at about the lowermost quarter length thereof and, as shown, slightly below the seal of the first reentrant tube 11 and the tubular sleeve 12. Spaced around said anode 15 and bearing thereagainst are a plurality of resilient supporting This construction is disclosed in the application of Nelson H. Stewart, Serial No. 578,244, filed December 1, 1931 and assigned to the same assignee as the present invention.

In accordance with my invention to provide a radiator rod of simple construction which may be firmly secured to the support sleeve 12 without applying torsional forces to said sleeve and particularly torsional forces of such magnitudes as to cause impairment of said sleeve or of the seal of said sleeve with said re-entrant tube 11, I have provided the following construction which is illustrative of my invention.

Accordingl the radiator rod may be composed of two essential separate sections and in the event that I employ a fin radiator in combination therewith, it may be in three essential separate sections. As shown, the radiator rod together with the fin radiator is composed of three sections consisting of a solid rod 30 of copper or the like, having a threaded nipple 31 at one end whose diameter is equal to the corresponding internal dimension of the recess in the nipple 13 of the support sleeve 12, a cylindrical sleeve 32 of copper of substantial thick ness and appreciable l ngth whose internal dia "leter is equal to the corresponding external dimension of the solid rod 30, and a fin radiator 33 having an opening whose diameter is the same as the diameter of the rod 30.

As shown, the rod 36 is firmly secured to the sleeve or support 12 by threadedly engaging the nipple 31 in the threaded recess of the nipple 13. Thereafter, the sleeve or cylindrical member 32, whose length is about two thirds that of the rod 30, is mounted upon the connecting rod or anode extension 30 by sliding said sleeve over said rod 30.

Subsequently, the fin radiator is slid over the rod 30 so that one extremity thereof abuts the adjacent end of said sleeve 32. Then finally a washer 34 is applied over the opening of the fin radiator whose length is, together with the length of the sleeve 32, somewhat greater than the length of the rod 30. The washer 34 is secured to the rod 30 by virtue of a stud bolt 35 being in engagement with the threads of the re cess 36 located on the lower end of the rod 30.

In a construction of this character by screwing the stud bolt 35 towards the upper end of the envelope there is applied a force in the direction of the longitudinal axis of the rod 30 which causes the fin radiator 33 together with the sleeve 32 to slide along the rod 30 and become associated with the support sleeve 12, with the upper surface or" the sleeve 32 being in firm contact with the shoulder of the sleeve 12. When this tightening operation is carried out the operator holds the fin radiator 33 in one hand to prevent rotation thereof and turns the stud bolt by means of a screw driver held in the other hand.

In a construction of this character it is evident that the radiator rod assembly may be firmly secured to the support coupling 12 without subjecting the support coupling to excessive torsional strains.

This invention is subject to modification and it is not to be limited to the exact construction threaded nipple, a shielding means supported by said base and surrounding a major portion of said coupling and extending below the place where the coupling is secured to said envelope, said anode having a threaded section screwed onto said nipple and having its lower edge contiguous with said shielding means, a rod having a threaded end screwed into the hollow of said nipple, a sleeve mounted on said rod and means cooperating with said rod to force said sleeve and support coupling towards each other.

2. In an X-ray tube comprising an envelope, an anode and a cathode therein, a support coupling hermetically sealed to said envelope and having a hollow nipple which is internally and externally threaded, said anode having a threaded portion secured onto the outer threaded section of said nipple, the lower edge of said anode being adjacent the upper face of said coupling, a rod having a threaded end secured to the inner threaded section of said nipple, a metallic sleeve slidably mounted on said rod, said sleeve having one end located closely adjacent said coupling and its other end located outside and beyond that end of said envelope carrying the coupling, a heat radiator slidably mounted on said rod, one end of said radiator being adjacent said other end of said sleeve, means cooperating with said rod and radiator to force said sleeve towards said coupling.

ROBERT T. HUMMEL. 

